1. Field of the Invention
The present invention relates to ink jet printers, and particularly to a head tend media and system for performing head tend operations such as cleaning or purging the print head on an ink jet printer.
2. Description of Related Art
Typical ink jet printers include a print head which is provided with a plurality of orifices. As the print head moves back and forth over the surface of a print media, ink is expelled through the orifices, or jets, and onto the print media at appropriate intervals to print the desired images, such as characters or graphics. Proper operation of such a printer depends on a uniform and predictable flow of ink through the orifices. Otherwise, the character or graphic being printed may have gaps, skips, or other flaws in areas printed by a faulty orifice.
One cause of faulty orifice operation is the presence of contaminants within the orifice, the ink supply channel leading to the orifice, or on the face of the print head which restrict or obstruct the flow of ink through the orifice. Accordingly, to ensure reliable operation of ink jet printers, it is necessary to keep the face of the print head, the orifices, and the supply channels free of paper dust, stray ink droplets, or other extraneous and undesirable material.
Bubbles within the ink supply channels can also result in restricted or intermittent ink flow through the orifices. Therefore, occasionally it may be desirable to purge ink from the print head in order to prime the orifices and eliminate an bubbles which may be present in the ink supply channel. Purging can also be used to expel old or unwanted ink, or other debris from the supply channels and orifices. However, during a purge operation, it is important to collect the expelled ink to prevent it from collecting on the face of the print head or on other parts of the printer.
Similarly, in solid ink printers, when the print head is being warmed up to operating temperature, ink may be discharged from the head as a result of natural expansion. In order to prevent contamination resulting from discharged ink collecting on the print head or other parts of the printer, any discharged ink should be quickly collected and removed from the printer.
Otherwise, if ink is allowed to collect, it may come into contact with the print media producing smudges or other undesirable marks. Further, if the ink is allowed to solidify within the printer, the solidified ink may break off producing particles of solidified ink which can plug an orifice, jam moving parts of the printer, or impede performance of the printer in some other fashion.
To alleviate the problems associated with contamination and ink build up on print heads several head tend devices and systems have been developed. For example, a variety of mechanisms for mechanically wiping print heads are available. A number of these wiping systems use a nonabsorbent wiper, such as a rubber disc or a steel knife edge, which is wiped across the face of the print head to remove accumulated dirt or ink. However, because the wiping element is nonabsorbent, these types of systems are not adequate for collecting and removing the quantities of ink which may be released during purge and warm up operations. Further, the nonabsorbent wiping element has only limited cleaning capabilities.
Other head tend systems have used absorbent wiping elements. Typically such systems include a spool of absorbent ribbon or tape which is moved across the surface of the print head. However, a printer using such a system must be provided with a drive system for moving the tape and maintaining proper tape tension and position. As a result of the additional moving parts necessary for the drive system, the cost, reliability, and size of the printer are adversely affected. Further, because the wiping media is typically stored on spools, or within cartridges, the wiping media is typically relatively small and thin. As a result, the amount of ink which can be absorbed by the small, thin wiping media is inherently limited.
Another head cleaning system utilizes a cleaning card and a card guide. The cleaning card has a solvent saturated foam strip attached near its bottom edge. The card guide is attached to the print head and is adapted to receive the card. The card guide is positioned such that as the card is manually inserted therein, the foam strip is pressed against the surface of the print head releasing some of the solvent and wiping the head. A drainage system is provided to drain the released solvent from the print head.
However, because the foam strip is relatively small and because it is saturated with solvent, its absorbance capacity is limited. Further, the card guide and the solvent drainage system require the presence of additional hardware within the printer. As with the systems described above, this additional hardware adds to the cost, size, and weight of the printer and may adversely affect the reliability and operation of the printer.